A. Field of the Invention
The field of the present invention relates generally to wind turbines, windmills and other wind powered machines that utilize the energy of the wind to produce rotational torque through an output shaft to generate electricity, operate a pump or accomplish other useful work. More particularly, the present invention relates to such machines that have a vertically disposed rotational axis and which utilize hinged sails to capture the energy of the wind and produce the desired rotational torque. Even more particularly, the present invention relates to such machines that are relatively simple and inexpensive to manufacture, require little ongoing maintenance and are effective at producing rotational torque even in low wind speed conditions.
B. Background
Motors and other machines for converting a source of input energy to an output in the form of rotational torque that is delivered through an output shaft have been generally available for many years. The rotational torque at the output shaft is commonly utilized to produce electricity via a generator or power a pump, grinding wheel or other machine, turn a wheel and operate other devices. The input energy for such machines has been provided by people, animals, moving water, gravity, blowing wind, fossil fuels, nuclear materials and a variety of other sources. Over the years, there has been a desire to have machines which utilize energy from readily available, clean and renewable sources, such as water, wind or the sun, instead of using the limited more polluting sources of energy, such as petroleum, coal, uranium and the like. With regard to machines which use the power of moving water or wind, these machines are generally configured to result in a weight or force differential, provided by the weight of the water or force of the wind, on opposite sides of the machine's wheel or fan blades in order to rotate a shaft fixedly connected to the wheel or fan blades. The ideal configuration for such machines is to have as much of a weight or force imbalance as possible on the opposite sides of the wheel or fan blades so that the machine will generate the maximum amount of rotational torque at the output shaft. In general, the components of water or wind powered machines are beneficially shaped and configured in an attempt to achieve this result.
With regard to producing electricity, apparatuses and systems for converting a source of energy to useful power for generating electricity have been generally available for many years. A common arrangement for generating electricity is a large power plant that delivers the produced electricity to the end user over long distance, often very long distance, transmission lines. As is commonly known, such power plants are very complicated and very expensive, requiring large capital investment in the power plant and the transmission lines. Presently, most large power plants rely on traditional sources of energy, such as oil, natural gas, coal, nuclear, stored water and the like to produce electricity. There is a strong effort to provide alternative apparatuses and systems to power machines, particularly generators for producing electricity, that utilize energy sources which have less environmental impact, generally by being more readily available, cleaner and, preferably, renewable. For instance, many people and organizations have been attempting to utilize wind, solar, tidal and geothermal resources as a source of power to operate generators for the production of electricity. Although such sources of energy have been well known and, to some extent, in use for many years, it has only been relatively recent that substantially increased efforts have been directed towards improving the efficiency of these energy systems so they may be capable of generating more electricity. Currently, such alternative energy systems are a relatively small percentage of the total electricity production.
In general, the increased push for apparatuses and systems that generate electricity without utilizing conventional, non-renewable and polluting energy sources is a direct result of an increase in the number of devices which are powered by electricity, such as computers, air conditioning, vehicles, audio systems, kitchen appliances and a vast number of other devices, and the rapid expansion in the number of people who desire to utilize such devices. As well known, the increase in the supply of electricity to meet this demand will have to be supplied by those apparatuses and systems that are available, which, at least presently, primarily rely on hydrocarbon-based fuels. In general, as the need for electricity increases, the supply of fuel to produce electricity is further reduced, the environmental impacts of utilizing certain fuels worsen and the cost of using electricity increases. Most experts expect that the demand for electricity will substantially increase during the foreseeable future. In addition, consumers generally expect that electricity will be available to them when they need it, whether to operate an appliance, energize a light source, operate a machine or provide power to operate motor vehicles.
Although electricity is most often produced and provided to the public by large power plants via long distance transmission lines, there is a need for the production of electricity at or very near the location where it is needed. One advantage of such electricity production is that it eliminates the requirement to transmit electricity over long distances, thereby eliminating the cost to build long distance transmission lines, the cost of acquiring the right-of-way for the land and the use of the land to support those lines. For areas that are somewhat off of the normal power grid, the cost of building the necessary transmission lines and the cost to maintain those lines can be significant. To be effective, however, an apparatus and system for localized production of electricity must be of sufficient size to supply the desired amount of electricity and must be able to reliably supply that electricity. Presently, small wind, water and solar generators and generating systems for localized production of electricity are generally not widely utilized.
With regard to wind generating apparatuses and systems, the most common type are those which utilize a wind “propeller” configuration having a horizontally disposed rotational axis around which a plurality of propellor vanes rotate in response to blowing wind. These types of wind energy machines, also referred to as windmills and horizontal axis wind turbines, are commonly utilized throughout the world. One limitation of these machines is that the horizontal axis through propeller must face in the direction from which the wind originates, which requires the machine to rotate the propeller so that it is always facing into the wind. Generally, this results in somewhat complicated machinery that requires significant capital investment and relatively high maintenance costs. Another common problem with horizontal axis wind energy machines is that the surface area available for contact with the wind is somewhat limited in order to reduce the weight associated with the propeller. In addition, horizontal axis wind energy machines must be geared and otherwise configured to account for the differing speeds of rotation at the center and at the outward tip of the propeller blades. As will be readily appreciated by persons skilled in the art, propeller blades are generally configured and intended to create thrust and are somewhat inefficient as wind current collectors.
Vertical axis wind energy machines have a plurality of flat surfaces which rotate around a vertically disposed rotational axis in response to blowing wind. One advantage of these machines is that they are generally self-aligning in that they do not need to be directed into the wind, as they will rotate around the center axis no matter which direction the wind originates. Another advantage of these machines over horizontal axis wind energy machines is that vertical axis wind energy machines generally work better under low wind speed conditions and, partially as a result thereof, can be utilized closer to the ground, such as on the roof of a building or the like. Presently available vertical axis wind energy machines typically utilize fixed blades that require careful aerodynamic design in order to obtain desirable levels of torque output, which generally requires the sacrifice of blade surface area for weight. In addition, most prior art vertical axis wind energy machines require relatively high wind speeds to start the rotational movement of the machine. To compensate for deficiencies in operation, most presently available vertical axis wind energy machines are somewhat complicated to operate and expensive to purchase and/or install.
What is needed, therefore, is an improved wind energy machine that is configured to more effectively and efficiently rotate wind collecting surfaces around a center axis to rotate an output shaft for use in generating electricity or to power another machine. The preferred wind energy machine will be able to more beneficially and efficiently produce rotational torque as a result of blowing wind. Preferably, an improved wind energy machine will be able to produce the desired work activity at relatively low wind speeds and be particularly suitable for localized production and use of such work activity, such as generation of electricity. The preferred wind energy machine should be relatively simple to install and operate and be relatively inexpensive to manufacture.